This invention generally relates to intravascular procedures, such as percutaneous transluminal coronary angioplasty (PTCA), and particularly to the exchange or support of guidewires during such procedures.
In typical PTCA procedures, a guiding catheter is positioned within a patient""s vasculature such that the distal end of the guiding catheter is disposed within the ostium. A guidewire is advanced through the guiding catheter and into the patient""s coronary arteries. The guidewire is maneuvered by advancing and rotating the distal tip which normally has an asymmetric xe2x80x9cJxe2x80x9d shape imposed on it to enable selection of various branches of the coronary vasculature. Once the guidewire is positioned in a desired location, a dilatation catheter is advanced over the guidewire into the patient""s coronary artery until the balloon on the distal extremity of the dilatation catheter is properly positioned across the lesion to be dilated. Once properly positioned across the lesion, the flexible,/relatively inelastic balloon on the dilatation catheter is inflated to a predetermined size with radiopaque liquid at relatively high pressures (e.g., generally 4-20 atmospheres or more) to dilate the stenosed region of the diseased artery. One or more inflations of the balloon may be required to complete the dilatation of the stenosis. After the last dilatation, the balloon is deflated so that the dilatation catheter can be removed from the dilated stenosis and blood flow can resume through the dilated artery.
One difficulty that can be encountered in the procedure above is the inability to cross the lesion or stenosis with the distal end of the guidewire. This can be due to a variety of circumstances, including, a tight stenotic lesion with insufficient lumen patency to allow passage of a guidewire. Also, the lesion may be completely blocked as is found with a chronic total occlusion (CTO) and the guidewire may require axial support at the distal end in order to cross such a CTO. It is also possible that a guidewire may not be suitably configured to cross a given lesion or stenosis. In such a case, there is a need to replace an in-place guidewire with another guidewire having a different structure, e.g. from a floppy-type design with a separate shaping ribbon to an intermediate or standard with a core wire which extends to the distal tip of the guidewire. The need to withdraw an in-place guidewire also occurs when the distal tip of the in-place guidewire needs to be reshaped to change the angle of attack to a branch coronary artery. Because of this, it is desirable for the physician to be able to exchange guidewires and support a pre-positioned guidewire to facilitate crossing of a difficult lesion.
In addition, a significant improvement in dilatation catheters has been the introduction of rapid exchange type dilatation catheters. These catheters have a short guidewire receiving sleeve or inner lumen extending through the distal portion of the catheter which extend from a distal guidewire port in the distal end of the catheter to a proximal guidewire port spaced proximal to the proximal end of the dilatation balloon. The proximal guidewire port is usually located at least about 10 cm and usually not more than about 50 cm from the distal guidewire port. A slit is some times provided in the catheter wall in fluid communication with the guidewire receiving inner lumen which extends from the second guidewire port, preferably to a location proximal to the proximal end of the inflatable balloon to aid in the removal of the catheter from a guidewire upon withdrawal of the catheter from the patient. The structure of the catheter allows for the rapid exchange of the catheter without the need for the use of an exchange wire or adding a guidewire extension to the proximal end of the guidewire.
Rapid exchange type dilatation catheters are described and claimed in U.S. Pat. No. 5,040,548 (Yock), U.S. Pat. No. 5,061,273 (Yock), U.S. Pat. No. 5,300,085 (Yock), U.S. Pat. No. 5,350,395 (Yock), U.S. Pat. No. 4,748,982 (Horzewski et al.), U.S. Pat. No. 5,154,725 (Leopold) and U.S. Pat. No. 5,346,505 (Leopold) which are incorporated herein in their entirety by reference.
However, one significant inconvenience with the use of rapid exchange type dilatation catheter systems is the inability to remove a guidewire already in place within a patient""s vasculature during an angioplasty procedure without losing access to the vascular location. There has been no convenient way in-which a replacement guidewire might be advanced through the vasculature and into the short guidewire receiving inner lumen in the distal extremity of a rapid exchange type dilatation catheter.
What has been needed is a convenient means to withdraw an in-place guidewire from a rapid exchange type dilatation catheter and either replace the in-place guidewire with another guidewire or to reposition the inplace guidewire within the rapid exchange type dilatation catheter.
The invention is directed generally to an elongate intracorporeal device for facilitating access for diagnostic devices, therapeutic devices, or the like which are advanced over a guidewire within a patient""s body. Specifically, the invention is directed to a catheter for support or exchange of a guidewire. An embodiment of a catheter with features of the invention has an elongate shaft with an inner lumen within shaft. The elongate shaft has a proximal end and a distal end with a proximal port of the inner lumen at the proximal end of the shaft and a distal port of the inner lumen at the distal end of the shaft. There is an intermediate port on the elongate shaft in fluid communication with the inner lumen disposed between the proximal port and the distal port. An optional longitudinal slit in an outer wall of the elongate shaft extends distally from the proximal port of the inner lumen at the proximal end of the elongate shaft. A longitudinal support member is secured to the elongate shaft in order to provide axial support to the catheter.
The distance from the distal end of the elongate shaft to the intermediate port can be about 15 to about 45 cm, specifically about 30 to about 40 cm. This allows the catheter to be loaded over a proximal end of a first guidewire with the distal end of the guidewire positioned within a patient""s body. In use, the proximal end of the first guidewire is backloaded into the distal port of the inner lumen of the elongate shaft and exits through the intermediate port. An exit tube can be disposed within the intermediate port to facilitate discharge of the proximal end of the guidewire from the intermediate port during the backloading process. The catheter can thus be loaded over the first guidewire and advanced distally over the first guidewire while leaving the distal end of the first guidewire positioned within the patient""s body. Once the catheter has been advanced distally to a desired position, the first guidewire may be withdrawn from the patient and a second guidewire front loaded into the proximal port of the inner lumen and advanced distally into the patient into the position that the first guidewire occupied prior to being withdrawn. Again, the second guidewire can be withdrawn from the patient and a third guidewire can be frontloaded into the proximal port, and so on. The proximal end of the elongate shaft of the catheter may then be pulled laterally with respect to the second guidewire such that a corresponding proximal end of the second guidewire emerges laterally from the longitudinal slit. The catheter can thereafter be withdrawn proximally while holding the proximal end of the second guidewire in fixed axial position, and peeling the catheter off of the second guidewire while the catheter is being retracted.
The process can then be repeated if it is desired to replace the second guidewire with a new third guidewire, and so on. In this way, the physician can exchange guidewires while maintaining access to a desired position within a patient""s body. In addition, the distal end of the elongate shaft can be advanced distally over a guidewire to a position which enables the distal end of the elongate shaft to provide axial support and pushability to the distal end of the guidewire. This can be used to facilitate advancement of the distal end of a guidewire across a tight stenosis, chronic total occlusion or the like.
In another embodiment of a catheter having features of the invention an elongate shaft of the catheter has a proximal end, a distal end, a first inner lumen and a second inner lumen, with both inner lumens being suitable for passage of a desired guidewire. The first inner lumen has a distal port at the distal end of the elongate shaft and an intermediate port at a position proximal of the distal end of the elongate shaft and distal of the proximal end of the elongate shaft. The second inner lumen has a distal port at the distal end of the shaft and a proximal port at the proximal end of the shaft. There is optionally a longitudinal slit in a wall of the elongate shaft, which is in fluid communication with the second inner lumen and which extends distally from the proximal port of the second inner lumen. A longitudinal support member is secured to the elongate shaft for axial support of the exchange catheter.